Correlation analyses
As shown in Table 2, HRV was not significantly correlated with RRStotal, Brooding, Reflection, BDI-II, MASQdepression, or DASSdepression, nor with Depressionstandardized. However, RRStotal, Brooding, and Reflection were significantly correlated with BDI-II, MASQdepression, and DASSdepression, and Depressionstandardized, indicating that the tendency to ruminate was associated with higher levels of depression symptoms. There was a significantly negative correlation between age and RRStotal, Brooding, and Reflection, which means that the tendency to ruminate gradually decreased with the increase of age. Similarly, age was negatively correlated with BDI-II and Depressionstandardized, respectively. The analyses with gender as the grouping variable found that the HRV was lower in women than in men (t (233.162) = 2.399, p = .017), and the RRStotal (t (1148) = -3.618, p < .001), Brooding (t (1148) = -3.649, p < .001) and Reflection (t (1148) = -2.895, p < .001) were higher in women than in men, but there were no differences in BDI-II (t (342) = -1.006, p = .315), DASSdepression (t (457) = .415, p = .678) and Depressionstandardized (t (1019) = -.403,p = .687). Sex differences in depression could not be investigated using the MASQdepression because all the participants were female. In addition, there was a significant difference in HRV between the types of physiological baseline measurement (t (1187) = -2.060, p = .040), showing lower HRV during resting baseline than during Vanilla baseline.